﻿//
// (C) Copyright 2009 Irantha Suwandarathna (iranthas@hotmail.com)
// All rights reserved.
//

/* Copyright (c) 2001-2008, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use _in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions _in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer _in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security;
using System.Security.Cryptography;
using System.IO;
using EffiProz.Core.Errors;
using EffiProz.Core.Lib;

namespace EffiProz.Core.Persist
{
    public class Crypto
    {
        byte[] encodedKey;
        byte[] encodedIv;
        string cipherName;
        SymmetricAlgorithm outCipher;
        SymmetricAlgorithm inCipher;

        private static SymmetricAlgorithm getAlgorithm(string cipherName)
        {
            if (cipherName.Equals("DES", StringComparison.OrdinalIgnoreCase))
            {
                return new DESCryptoServiceProvider();
            }
            else if (cipherName.Equals("TripleDES", StringComparison.OrdinalIgnoreCase))
            {
                return new TripleDESCryptoServiceProvider();
            }
            else if (cipherName.Equals("Aes", StringComparison.OrdinalIgnoreCase))
            {
                return new AesCryptoServiceProvider();
            }
            else if (cipherName.Equals("Rijndael", StringComparison.OrdinalIgnoreCase))
            {
                return new RijndaelManaged();
            }
            else
            {
                throw Error.error(ErrorCode.X_S0531);
            }
        }

        public Crypto(String keyString, String iVString, String cipherName)
        {

            this.cipherName = cipherName;
            encodedKey =
                StringConverter.hexStringToByteArray(keyString);
            encodedIv =
                StringConverter.hexStringToByteArray(iVString);

            inCipher = getAlgorithm(cipherName);
            outCipher = getAlgorithm(cipherName);

            try
            {
                inCipher.Key = encodedKey;
                outCipher.Key = encodedKey;
                inCipher.IV = encodedIv;
                inCipher.IV = encodedIv;
            }
            catch (CryptographicException e)
            {
                throw Error.error(ErrorCode.X_S0531, e);
            }

        }

        public Stream getInputStream(Stream _in)
        {
            lock (this)
            {
                if (inCipher == null)
                {
                    return _in;
                }

                try
                {

                    return new CryptoStream(_in, inCipher.CreateDecryptor(encodedKey,encodedIv), CryptoStreamMode.Read);
                }
                catch (Exception e)
                {
                    throw Error.error(ErrorCode.X_S0531, e);
                }
            }
        }

        public Stream getOutputStream(Stream _out)
        {
            lock (this)
            {
                if (outCipher == null)
                {
                    return _out;
                }

                try
                {

                    return new CryptoStream(_out, outCipher.CreateEncryptor(encodedKey, encodedIv), CryptoStreamMode.Write);
                }
                catch (CryptographicException e)
                {
                    throw Error.error(ErrorCode.X_S0531, e);
                }
            }
        }

        public byte[] decode(byte[] source, int sourceOffset,
                                       int length)
        {
            lock (this)
            {
                if (inCipher == null)
                {
                    return null;
                }
               
                try
                {
                    ICryptoTransform decryptor = inCipher.CreateDecryptor(encodedKey, encodedIv);
                    return decryptor.TransformFinalBlock(source, sourceOffset, length);                  

                }
                catch (Exception e)
                {
                    throw Error.error(ErrorCode.X_S0531, e);
                }
               
            }
        }


        public byte[] encode(byte[] source, int sourceOffset,
                                       int length)
        {
            lock (this)
            {
                if (inCipher == null)
                {
                    return null;
                }
          
                try
                {
                    ICryptoTransform encryptor = inCipher.CreateEncryptor(encodedKey, encodedIv);
                    return encryptor.TransformFinalBlock(source, sourceOffset, length);                   
                   
                }
                catch (Exception e)
                {
                    throw Error.error(ErrorCode.X_S0531, e);
                }
            }
        }

        public static byte[] getNewKey(String cipherName)
        {

            SymmetricAlgorithm cipher = getAlgorithm(cipherName);
            cipher.GenerateKey();
            byte[] raw = cipher.Key;
            return raw;
        }

        public static byte[] getNewIv(String cipherName)
        {

            SymmetricAlgorithm cipher = getAlgorithm(cipherName);
            cipher.GenerateIV();
            byte[] raw = cipher.IV;
            return raw;
        }

        public int getEncodedSize(int size)
        {
            int blocks = size / outCipher.BlockSize;
            return (blocks + 1) * outCipher.BlockSize;
            
        }
    }
}
